Axial compressor

ABSTRACT

An adjustably mounted structural part is disposed between the casing and rotor concentrically of each labyrinth seal to allow a centering adjustment to be made in the labyrinth seal formed by the internal surfaces in the part and the rings on the rotor. Wedge-shaped shim blocks and shims are used to effect the adjustment of each structural part on the casing. One or more shim plates can be used to adjust the axial relation between a structural part and casing.

United States Patent Benz [ AXIAL COMPRESSOR [75] Inventor: HansBenz,Winterthur,

YEZE1EEI [73] Assignee: Brown Boveri-Sulzer Turbomachinery Ltd., Zurich,Switzerland 22 Filed: Aug. 23, 1973 211 Appl. No.: 390,896

[30] Foreign Application Priority Data Sept. 8, 1972 Switzerland13194/72 [52] U.S. C1 415/113, 415/171, 277/53, 415/199 R [51 I Int. Cl.F04d 29/08 [58] Field of Search 277/53. 54, 55, 56; 415/131, 132,136,19911.21) R, 170 R. 171, 172, 113

[56] References Cited UNITED STATES PATENTS 137,471 4/1873 Meyers 1.415/132 1,227,141 5/1917 Hoover 415/131 [451 Feb. 11,1975

1,756,958 5/1930 Schmidt 415/131 2.123.818 7/1938 Wegmann 277/553,503,616 3/1970 Hickey 277/53 3,647,311 3/1972 Wootton 415/1713,773,430 11/1973 Canova et :11 415/131 FOREIGN PATENTS OR APPLlCATlONS181,635 6/1922 Great Britain 277/54 292,553 9/1928 Great Britain 415/131Primary ExaminerHenry F. Raduazo Attorney, Agent, or FirmKenyon & KenyonReilly Carr & Chapin 8 Claims, 3 Drawing Figures 1 AXIAL COMPRESSOR Thisinvention relates to an axial compressor and particularly to thecentering of a rotor within a casing of an axial compressor.

Axial compressors have been known to have a stator blade support whichis radially centered in a casing as well as a rotor which is centeredwith respect to the stator blade support be means of bearings. In orderto simplify the sealing of the compressor, the stator blade support ofsome axial compressors has not been mounted so as to be adjustable withrespect to the casing but has merely been mounted so as to be axiallyslidable under thermal expansion forces. This measure, however, requiresthe rotor to be centered with respect to the stator blade support, forexample by displacement of the blocks in which the rotor bearings aremounted, fine adjustment being performed in the radial bearingsthemselves. Compressors constructed in this manner frequently give riseto difficulties relating to the adjustment of the usually used labyrinthseals between the casing and the rotor since these seals require closertolerances than those tolerances required by the blade clearance of therotor blades.

Accordingly, it is an object of the invention to facilitate theadjustment of labyrinth seals in axial compressors.

Briefly, the invention provides an axial compressor of the type having acasing, stator blade support radially centered within the casing, rotorand a labyrinth sealing means between the rotor and casing with astructural part to simplify the making of an adjustment in the sealingmeans. This structural part is mounted on the easing in an adjustablemanner and has an inner annular surface surrounding the rotor in which aplurality of annular grooves are formed to cooperate with a plurality ofradially directed rings on the rotor to define the labyrinth sealingmeans. The structural part is disposed to encircle one end of the rotorwhile a duplicate structural part envelops an opposite end of the rotor.

In order to effect an adjustment of one of the sealing means, therespective structural part is manuevered within the casing to re-orientthe annular grooves to achieve a centered relationship with the radialrings on the rotor after the rotor is put in place. To this end, meanssuch as a plurality of shim blocks are disposed between the structuralpart and the casing to center the structural part radially with respectto the rotor with at least one shim between each shim block and at leastone of the structural part and casing. The shims can be of varyingthickness, and it is advantageous if four shim blocks are distributedover the external circumference by screw-mounting on the structuralparts. Since an axial adjustment of the labyrinth sealing means isfrequently required in addition to the radial adjustment, shims can beprovided between the structural parts and the casing to adjust the axialrelation of the structural parts to the casing.

These and other objects and advantages of the invention will become moreapparent from thee following detailed description taken in conjunctionwith the accompanying drawing in which:

FIG. I diagrammatically illustrates a vertical sectional view through anaxial compressor according to the invention;

FIG. 2 illustrates to an enlarged scale the section A of FIG. 1; and

FIG. 3 illustrates a view taken along line IIIIII of FIG. 2.

Referring to FIG. I, the axial compressor has a stator blade support 1radially centered in a longitudinally split casing 2. An annularprojection 3 of the support 1 bears on a suction side end of thecompressor in a corresponding groove of a wall 4 which is associatedwith the casing 2 and defines a suction volute 5 with respect to themiddle part of the casing 2.

The stator blade support 1 is also radially supported in the casing 2 onthe delivery side and bears via a collar 7 on the mating surface ofashoulder 8 of the casing wall which defines a delivery volute 9. A gap11 which permits axial motion of the delivery end of the stator bladesupport 1 is provided between the delivery side endface of the statorblade support 1 and a flared guide wall 10 of a diffuser which definesthe transition into the delivery volute 9 in order to allow for thermalexpansion.

In addition, a rotor 12 is journalled into two bearing blocks 13 whichare separate from the casing 2. In order to effect a first roughapproximation of the blade clearance of the rotor 12 with respect to theblade sup port I, the bearing blocks 13 have means for adjusting thebearing blocks relative to the casing 2. For example shims (not shown)of varying thickness are inserted between the bearing blocks 13 andtheir support surfaces and a lateral dislacement of the bearing blocks13 is made before the blocks 13 are mounted on their support surfaces.Fine adjustment of the blade clearance is obtained in known manner (notshown) in the bearings themselves.

The rotor 12 is provided with a central portion which supports blades14, and with stepped shoulders 15, 16 on either side of the centralportion which, in turn, support sheet metal rings or plates 17 oflabyrinth seals (FIG. 2). The rings 17 co-operate with stepped matingsurfaces 18 of a split structural part 20, 21 respectively on thesuction side and on the delivery side of the compressor. These steppedsurfaces 18 define annular grooves, each of which receives a ring 17 asshown, between annular lands, each of which is concentric to a ring 17.The parts 20, 21 which also define the interior of the inlet anddiffuser are adjustably mounted on the casing 2. Referring to FIGS. 2and 3, in order to center each structural part 20 with respect to thelabyrinth seal rings 17, four shim blocks 22 are disposed between thecasing 2 and the part 20. As shown in FIG. 3, the shim bloc ks 22 aredisposed in offset configuration with respect to the vertical andhorizontal because of the horizontal division of the casing 2 and thestructural parts 20, 21. Each block 22 is of a wedge-shape andcooperates with individual shims 24 of varying thickness.

The shim blocks 22 are inserted in corresponding grooves 23 of thestructural parts 20, 21, respectively, and are retained therein by meansof screw fasteners (not shown). Before being installed in the casing 2,the internal parts 20, 21 together with the shim blocks 23 screw-mountedthereon, are machine-turned in order to eliminate all eccentricity.After being installed, the structural parts 20, 21 are located in thecasing 2 by means of screw fasteners 25 of which one is shown in FIG. 2.

In some circumstances, axial adjustment of the labyrinth seals isrequired in addition to the central adjustment. To this end, shim plates26, whose number and- /or thickness may be varied, are provided on theendfaces of the structural parts 20, 21 which are disposed outwardly tothe casing 2.

What is claimed is:

1. In an axial compressor a casing,

a stator blade support radially centered within said casing;

a bladed rotor rotatably mounted within said casing and stator bladesupport;

a structural part at least radially adjustably mounted on said casingbetween said casing and said rotor; and

a labyrinth seal between said structural part and said rotor and meansto center said structural part radially with respect to said rotor.

2. In an axial compressor as set forth in claim 1 said labyrinth sealincludes a plurality of radially directed rings on said rotor and aplurality of annular grooves in said structural part, each groovereceiving a respective ring in spaced relation.

3. In an axial compressor as set forth in claim 1 a bearing block ateach end of said rotor, each bearing block having means for adjustablymounting the bearing block with respect to said casing and said statorblade support for centering of said rotor relative to said stator bladesupport.

4. In an axial compressor as set forth in claim 1, said rotor having acentral portion having rotor blades thereon and a pair of saidstructural parts, each part encircling an opposite end of said rotorrelative to said central portion.

5. In an axial compressor a casing,

a stator blade support radially centered within said casing;

a rotor rotatably mounted within said casing and stator blade support;

a structural part adjustably mounted on said casing between said casingand said rotor;

a labyrinth seal between said structural part and said rotor; and

a plurality of shim blocks disposed between said structural part andsaid casing in circumferentially spaced relation about said structuralpart, and at least one shim between each shim block and at least one ofsaid structural part and said casing for centering said seal relative tosaid rotor.

6. In an axial compressor as set forth in claim 5 having four of saidshim blocks fixedly disposed in said structural part.

7. In an axial compressor as set forth in claim 5 at least one shimplate between said structural part and said casing for adjusting saidpart axially of said casing and said sealing means axially of saidrotor.

8. In an axial compressor a longitudinally split casing;

a stator blade support radially centered within said casing to define asuction volute on one side and a delivery volute on an opposite side;

a rotor rotatably mounted within said casing and stator blade supportand having blades thereon; and

a labyrinth sealing means between said casing and said rotor including astructural part adjustably on said casing for radial movement and havingan inner annular surface surrounding said rotor with a plurality ofannular grooves therein and a plurality of radially directed rings onsaid rotor cooperating with said grooves and means to center saidstructural part radially with respect to said rotor.

1. In an axial compressor a casing, a stator blade support radiallycentered within said casing; a bladed rotor rotatably mounted withinsaid casing and stator blade support; a structural part at leastradially adjustably mounted on said casing between said casing and saidrotor; and a labyrinth seal between said structural part and said rotorand means to center said structural part radially with respect to saidrotor.
 2. In an axial compressor as set forth in claim 1 said labyrinthseal includes a plurality of radially directed rings on said rotor and aplurality of annular grooves in said structural part, each groovereceiving a respective ring in spaced relation.
 3. In an axialcompressor as set forth in claim 1 a bearing block at each end of saidrotor, each bearing block having means for adjustably mounting thebearing block with respect to said casing and said stator blade supportfor centering of said rotor relative to said stator blade support.
 4. Inan axial compressor as set forth in claim 1, said rotor having a centralportion having rotor blades thereon and a pair of said structural parts,each part encircling an opposite end of said rotor relative to saidcentral portion.
 5. In an axial compressor a casing, a stator bladesupport radially centered within said casing; a rotor rotatably mountedwithin said casing and stator blade support; a structural partadjustably mounted on said casing between said casing and said rotor; alabyrinth seal between said structural part and said rotor; and aplurality of shim blocks disposed between said structural part and saidcasing in circumferentially spaced relation about said structural part,and at least one shim between each shim block and at least one of saidstructural part and said casing for centering said seal relative to saidrotor.
 6. In an axial compressor as set forth in claim 5 having four ofsaid shim blocks fixedly disposed in said structural part.
 7. In anaxial compressor as set forth in claim 5 at least one shim plate betweensaid structural part and said casing for adjusting said part axially ofsaid casing and said sealing means axially of said rotor.
 8. In an axialcompressor a longitudinally split casing; a stator blade supportradially centered within said casing to define a suction volute on oneside and a delivery volute on an opposite side; a rotor rotatablymounted within said casing and stator blade support and having bladesthereon; and a labyrinth sealing means between said casing and saidrotor including a structural part adjustably on said casing for radialmovement and having an inner annular surface surrounding said rotor witha plurality of annular grooves therein and a plurality of radiallydirected rings on said rotor cooperating with said grooves and means tocenter said structural part radially with respect to said rotor.